Policy decomposition for collaborative access control

With the advances in web service techniques, new collaborative applications have emerged like supply chain arrangements and coalition in government agencies. In such applications, the collaborating parties are responsible for managing and protecting resources entrusted to them. Access control decisions thus become a collaborative activity in which a global policy must be enforced by a set of collaborating parties without compromising the autonomy or confidentiality requirements of these parties. Unfortunately, none of the conventional access control systems meets these new requirements. To support collaborative access control, in this paper, we propose a novel policy-based access control model. Our main idea is based on the notion of policy decomposition and we propose an extension to the reference architecture for XACML. We present algorithms for decomposing a global policy and efficiently evaluating requests